It is known to control the air fuel ratio of an internal combustion engine using various air fuel control strategies. Factors such as ambient air pressure, mass air flow, and intake air temperature have been used in the process of controlling air fuel ratio for an internal combustion engine.
Proper operation of a catalyst processing the exhaust gas from an internal combustion engine depends, in part, upon the air fuel ratio supplied to the engine. Associated with the downstream flow of exhaust gas and the catalyst it is known to use an exhaust gas oxygen sensor to sense the concentration of oxygen in the exhaust gas. Knowledge of the exhaust gas oxygen concentration can be used to control the air fuel ratio.
Previous approaches to estimating the temperature of a heated exhaust gas oxygen sensor have failed to take into consideration the effect of a variable length exhaust pipe enabling two paths of exhaust gas flow.